The disclosures of the following priority application are herein incorporated by reference:
Japanese Patent Application No. 10-67019 filed Mar. 17, 1998
Japanese Patent Application No. 11-181531 filed Jun. 28, 1999
1. Field of the Invention
The present invention relates to an image-capturing apparatus and an electronic still camera having an image-capturing element held by a holder for mounting the image-capturing element to the body. In addition, the present invention relates to a method and an apparatus for processing the mounting surface of the holder.
The present invention also relates to a metal member contact structure, and more specifically, it elates to a contact structure of a plurality of types of metal materials having different corrosion potentials, and an image-capturing apparatus and a camera adopting this contact structure.
2. Description of the Related Art
In an electronic still camera, a subject image from a photographic lens must be accurately formed on the image-capturing element in order to obtain a high quality image. The image-capturing element, which is held in a package, is mounted at the camera body by attaching the package to the camera body. However, since the dimensions of the light-receiving surface of the image-capturing element and the mounting surface of the package include errors that occur during the production process, the desired degree of dimensional accuracy cannot be achieved simply by attaching the package to the mounting surface of the camera body. Thus, the position of the image-capturing element relative to the photographic lens is adjusted or the position of the photographic lens is adjusted with respect to the image-capturing element after attaching the package to the camera body.
In the case of a camera with an interchangeable lens such as a single lens reflex camera, the interchangeable lens is mounted at the lens mount surface, which necessitates a mounting adjustment to be performed to ensure that the image-capturing element is mounted at a specific position relative to the lens mount surface. For this purpose, in the prior art, the image-capturing element package is fitted at the camera body together with a positional adjustment mechanism, a reference pattern is projected on the image-capturing element for display on a monitor and the position of the image-capturing element is adjusted with the positional adjustment mechanism while checking the image on the monitor.
The positional adjustment mechanism, which may be provided with, for instance, three screws located at the individual apexes of a triangular shape and a spring to take up slack, adjusts the position of the image-capturing element by advancing or retracting the three screws.
However, if the positional adjustment mechanism is housed in the camera body together with the image-capturing element as in the prior art, the camera will become large. In addition, it will be necessary to perform readjustment when the image-capturing element is mounted again after it has been detached for maintenance and inspection of the camera, which results in poor operability and poor maintainability.
An object of the present invention is to provide an image-capturing apparatus and an electronic still camera that achieve improvements in operability and maintainability by eliminating the necessity for a positional adjustment mechanism for the image-capturing element.
In order to achieve the object described above, the electronic still camera according to the present invention is provided with an image-capturing element that receives light from a subject image entering into a camera body through a photographic lens and a holder that holds the image-capturing element to secure it to the camera body, with a camera-side mounting surface formed at the camera body in reference to the image-forming plane of the photographic lens, a holder-side mounting surface formed at the holder relative to the light-receiving surface of the image-capturing element and the light-receiving surface aligned with the image-forming plane by placing the camera-side mounting surface and the holder-side mounting surface in contact with each other and mounting the image-capturing element at the camera body.
Alternatively, the electronic still camera according to the present invention is provided with an image-capturing element that receives light from a subject image entering into the camera body through an interchangeable photographic lens and a holder that holds the image-capturing element to secure it to the camera body, with a camera-side mounting surface formed at the camera body in reference to a mounting surface for the photographic lens formed at the camera body, a holder-side mounting surface formed at the holder relative to the light-receiving surface of the image-capturing element and the light-receiving surface aligned with the image-forming plane by placing the camera-side mounting surface and the holder-side mounting surface in contact with each other and mounting the image-capturing element at the camera body.
In either of these electronic still cameras, the camera body may be constituted of a material having a first corrosion potential with mounting seats constituted of a material having a second corrosion potential higher than the first corrosion potential secured to the camera body and the holder may be constituted of a material having a third corrosion potential higher than the second corrosion potential. For instance, the camera body may be constituted of a magnesium alloy, the mounting seats may be constituted of an aluminum alloy and the holder may be constituted of brass.
The mounting surface for the photographic lens extends in the direction perpendicular to the optical axis, the camera-side mounting surface is parallel to the mounting surface for the photographic lens and the holder-side mounting surface extends parallel to the light-receiving surface of the image-capturing element.
The camera-side mounting surface and the holder-side mounting surface each include a contact surface that defines the holder position relative to the camera body within a plane extending perpendicular to the optical axis.
Another object of the present invention is to provide a method and an apparatus for facilitating the processing of an mounting surface of a holder to be attached to an image-capturing apparatus or an electronic still camera.
In order to achieve the object described above, the method for processing a holder-side mounting surface according to the present invention includes a step in which a specific pattern is projected at an image-capturing element held by a holder, a step in which an image signal from the image-capturing element at which the pattern is being projected is input, a step in which a position of the holder-side mounting surface relative to a cutter is calculated based upon the image signal thus input and a step in which the holder-side mounting surface is machined with the cutter by moving the holder in conformance to the calculated position.
Alternatively, in order to achieve the object described above, the method for processing a holder-side mounting surface according to the present invention comprises a step in which a focal point adjustment is implemented for a microscope whose focal point has been adjusted in advance to the holder-side mounting surface to adjacent the focal point to a light-receiving surface of an image-capturing element held by a holder, a step in which the quantity of focal adjustment misalignment at the microscope occurring during the focal adjustment is detected, a step in which a position of the holder-side mounting surface relative to a cutter is calculated based upon the misalignment quantity thus detected and a step in which the holder is moved in conformance to the calculated position to process the holder-side mounting surface with the cutter. In this processing method, the cutter is positioned so that it is capable of machining the holder-side mounting surface that has not been machined.
The apparatus for processing a holder-side mounting surface according to the present invention comprises an optical system that projects a specific pattern at an image-capturing element held by a holder, a cutter that machines the holder-side mounting surface, a calculation circuit that, with an image signal from the image-capturing element at which the pattern is being projected input, calculates a position of the holder-side mounting surface relative to the cutter based upon the image signal thus input and a holder drive device that moves the holder in conformance to the calculated position to machine the holder-side mounting surface with the cutter.
Alternatively, the apparatus for processing a holder-side mounting surface according to the present invention comprises a microscope whose focal point can be adjusted to the holder-side mounting surface and a light-receiving surface, a cutter that is positioned to machine the holder-side mounting surface to be processed and machines the holder-side mounting surface, a calculation circuit that detects the quantity of misalignment in focal adjustment relative to both the holder-side mounting surface and the light-receiving surface and calculates a position of the holder-side mounting surface relative to the cutter based upon the misalignment quantity in the focal adjustment thus detected and a holder drive device that moves the holder in conformance to the calculated position to machine the holder-side mounting surface with the cutter.
In addition, in order to achieve the object described above, in the image-capturing apparatus according to the present invention provided with an image-capturing element that receives light of an optical image that advances within a body through an image-forming optical system and a holder that holds the image-capturing element and attaches it to the body, a body-side mounting surface is formed at the body relative to the image-forming plane of the image-forming optical system, a holder-side mounting surface is formed at the holder relative to the light-receiving surface of the image-capturing element and the light-receiving surface and the image-forming plane are aligned by mounting the image-capturing element at the body with the body-side mounting surface and the holder-side mounting surface placed in contact with each other. The holder-side mounting surface of this image-capturing apparatus, too, can be achieved through the processing method described earlier. Furthermore, a processing method adopting this processing method constitutes one mode of the present invention.
In the image-capturing apparatus described above, the body may be constituted of a material having a first corrosion potential with mounting seats constituted of a material having a second corrosion potential higher than the first corrosion potential secured to the body and the holder may be constituted of a material having a third corrosion potential higher than the second corrosion potential. For instance, the body may be constituted of a magnesium alloy, the mounting seats may be constituted of an aluminum alloy and the holder may be constituted of brass.
A still further object of the present invention is to provide a metal member contact structure that minimizes the occurrence of corrosion and facilitates the use of a material such as a magnesium alloy, which has a low corrosion potential and easily becomes corroded, and also to provide an image-capturing apparatus and a camera adopting this contact structure.
The present invention is adopted in a metal member contact structure in which a first metal member having a first corrosion potential, a second metal member having a second corrosion potential and a third metal member having a third corrosion potential come in contact with one another. The object described above is achieved by ensuring that the level of the second corrosion potential is between the first corrosion potential and the third corrosion potential and by placing the third metal member in contact with a machined surface formed through machining at the second metal member after the second metal member is secured to the first metal member.
The second metal member may be secured to the first metal member, which may be constituted of a magnesium alloy, through insert molding, outsert molding, caulking, press fitting, screwing or bonding.
The metal member contact structure according to the present invention described above may be adopted in an image-capturing apparatus. In such a case, the first metal member constitutes the body of the image-capturing apparatus and the second metal member constitutes a mounting member employed to attach the third metal member. In the image-capturing apparatus, it is desirable to machine the second metal member in such a manner that the image-forming plane of the photographic lens and the light-receiving surface of the image-capturing element held by the third metal member become substantially aligned with each other when the third metal member is placed in contact with the machined surface of the second metal member.
When adopting the present invention in a camera with a silver halide film (hereinafter referred to as a silver halide film camera), the first metal member constitutes the camera body, and the second metal member constitutes a member employed to position photographic film to be loaded along its thicknesswise direction in the vicinity of the exposure surface of the photographic film. In this camera, the second metal member should be machined so that the image-forming plane of the photographic lens and the exposure surface of the photographic film are substantially aligned with each other when the third metal member is placed in contact with the machined surface of the second metal member.
In another camera according to the present invention, which comprises a first member constituted of a magnesium alloy and a second member constituted of a material different from that constituting the first member, the second member is machined after it is secured to the first member.